- The structural configuration of the MCR-A GBS is a first of its type.
- Designed to be installed with minimum assistance from offshore crane vessels.
- A performance based design approach was chosen to deal with the site’s high seismic demand.
The Magtymguly Collector Riser (MCR-A) gravity based structure (GBS) is a 7,000 tonne fixed offshore steel gravity based structure located in Magtymguly field. The platform is located in approximately 67m water depth and 60km offshore Turkmenbashi in the Caspian Sea.
Arup’s services included detailed engineering design, structural engineering, naval architecture, installation design, geotechnical engineering and seismic engineering for the substructure. Arup also provided construction support during fabrication and installation support.
The configuration of the MCR-A steel gravity based platform presents a first of its type. The platform was designed to be self installed without the need for large and expensive offshore crane vessels.
The GBS is configured of large steel plated panels and more traditional tubular jacket type structures. The steel panels are formed to create large hollow pontoon sections that enable the structure to float during installation. The pontoon sections were then ballasted with water to lower the structure to the seabed. The GBS uses shallow skirted foundations that are installed via suction, eliminating the need for piles and piling equipment, and simplifies removal at the end of the field life
Our multidisciplinary team overcame a number of challenges including advanced dynamic time history seismic modelling, designing the unique suction skirted gravity based foundation in stiff clays and predicting global wave loads for combined slender and larger volume members.
Arup performed complex buckling and collapse analysis of the thin shell plated structures for all permanent and temporary load cases, including load-out, transportation, installation, environmental in-place and seismic load conditions to predict the structural response during an earthquake event.
The MCR-A platform is a permanent structure. However, the platform can be easily decommissioned and removed by reversing the installation methodology. The pontoon type substructure has the buoyancy and marine stability to be re-floated and towed back to shore for dismantling without heavy lifting or cutting equipment to encourage the efficient removal and ultimate resuse of the substructure or its materials at the end of its design life.